Wietse Venema:
> You can do
>
> ndd /dev/tcp \?
>
> to find out what parameters are supported. On my Solaris9 and
> Solaris10 test boxes it is called tcp_wscale_always.
>
> According to Solaris10 documentation:
>
> When this parameter is enabled, which is the default setting
> [since Solaris10], TCP always sends a SYN segment with the
> window scale option, even if the window scale option value is
> 0.
With the default tcp_wscale_always setting, making a connection
from a Solaris 10 box to FreeBSD 8.0:
20:13:59.808828 IP 168.100.189.17.32799 > 168.100.189.10.25: Flags
[S], seq 118377775, win 49640, options [mss 1460,nop,wscale
0,nop,nop,sackOK], length 0
20:13:59.808892 IP 168.100.189.10.25 > 168.100.189.17.32799: Flags
[S.], seq 538094055, ack 118377776, win 65535, options [mss
1460,nop,wscale 3,sackOK,eol], length 0
20:13:59.809327 IP 168.100.189.17.32799 > 168.100.189.10.25: Flags
[.], ack 1, win 49640, length 0
Same system with tcp_wscale_always set to zero:
20:14:52.736959 IP 168.100.189.17.32800 > 168.100.189.10.25: Flags
[S], seq 131413865, win 49640, options [mss 1460,nop,nop,sackOK],
length 0
20:14:52.737016 IP 168.100.189.10.25 > 168.100.189.17.32800: Flags
[S.], seq 3072042607, ack 131413866, win 65535, options [mss
1460,sackOK,eol], length 0
20:14:52.737581 IP 168.100.189.17.32800 > 168.100.189.10.25: Flags
[.], ack 1, win 49640, length 0
Thus, Solaris 10 does not send wscale, and neither should the
remote server.
If this does not make your mail move, then you need to collect
another tcpdump recording.
In that case mail was not moving because of multiple problems.
Wietse
